Here's a small tutorial on adding planters you find inside the default houses to your modification via the creation kit if your making your mod to use hearthfire components.

• Make a Utility Cell for your mod.
  This cell is a container cell to hold objects you don't want the models loaded of or sounds to be played in the active cell. from the menu select World->Cells, make sure interiors is selected, then right click in the list, click New, and name the cell ( yourmodname_utilitycell is a good unique name). Set lighting if you wish, and give it a string name (interior data) if you wish but its not nessasary. click apply, and ok.
  
• Adding the soil for planting.
  The soil object is just a little dirt mound like what is used in the world space for setting up plants for farms, except a little different. In the Object window we want to go to WorldObjects->Activator->and search for BYOHPlanterSoil, add this to your scene where you want the player to be able to plant a plant and give it a unique name like "plantsoil01" and number them in sequence (to help resolve problems). rinse and repeat for how many ever plantable spots you want (note: you can do this for your farmable area outside too!).
  
• Adding the Actor for planting soils.
  Switch into your utility cell you created in step one. once you have it loaded, we will need to add the actor to the area, so in the object window go to Actors->Actor and search for BYOHPlanterNPC, add this to the utility cell and give the actor a unique name, numbered in sequence as well like the planter soils you added. Add one for each planter soil you created.
  
• Linking The Soil and the Planting Soils
  Now we need to switch back to the world space where we added the planter soils. you'll need to do this to each planter soil. Right click the planter soil and click edit, then go to the Linked Ref tab. In the 'refrences' right click and click new (or double click). In 'Cell' select your utility cell, and in Ref select the planter NPC who's number corresponds with the soils name (i.e. planterNPC01 for plantsoil01). leave keyword blank. and click 'ok', rinse and repeat for each planter soil you created.
  
• Save your Mod and test it!
  at this point you should save your mod and test it, i'm not sure what the time frame is for the plants to grow, i just planted some plants, wandered around Skyrim (fast travel) for 3 days to pass then came back and saw all my wonderful new plants all grown

Hope this helps some of you who might of been trying to figure out how to duplicate the planters you find inside the default houses.